Code Quality

Ensuring your project’s code stays simple, readable and easy to contribute to can be problematic. With the help of GitLab CI/CD, you can analyze your source code quality using GitLab Code Quality.

Code Quality:

Going a step further, GitLab can show the Code Quality report right in the merge request widget area:

Code Quality Widget

For more information, see the Code Climate list of Supported Languages for Maintainability.

Use cases

For instance, consider the following workflow:

  1. Your backend team member starts a new implementation for making a certain feature in your app faster.
  2. With Code Quality reports, they analyze how their implementation is impacting the code quality.
  3. The metrics show that their code degrade the quality in 10 points.
  4. You ask a co-worker to help them with this modification.
  5. They both work on the changes until Code Quality report displays no degradations, only improvements.
  6. You approve the merge request and authorize its deployment to staging.
  7. Once verified, their changes are deployed to production.

Example configuration

Caution: The job definition shown below is supported on GitLab 11.11 and later versions. It also requires the GitLab Runner 11.5 or later. For earlier versions, use the previous job definitions.

This example shows how to run Code Quality on your code by using GitLab CI/CD and Docker.

First, you need GitLab Runner with:

Once you set up the Runner, include the CodeQuality template in your CI config:

include:
  - template: Code-Quality.gitlab-ci.yml

The above example will create a code_quality job in your CI/CD pipeline which will scan your source code for code quality issues. The report will be saved as a Code Quality report artifact that you can later download and analyze. Due to implementation limitations we always take the latest Code Quality artifact available.

It is also possible to override the URL to the Code Quality image by setting the CODE_QUALITY_IMAGE variable. This is particularly useful if you want to lock in a specific version of Code Quality, or use a fork of it:

include:
  - template: Code-Quality.gitlab-ci.yml

code_quality:
  variables:
    CODE_QUALITY_IMAGE: "registry.example.com/codequality-fork:latest"

By default, report artifacts are not downloadable. If you need them downloadable on the job details page, you can add gl-code-quality-report.json to the artifact paths like so:

include:
  - template: Code-Quality.gitlab-ci.yml

code_quality:
  artifacts:
    paths: [gl-code-quality-report.json]

The included code_quality job is running in the test stage, so it needs to be included in your CI config, like so:

stages:
  - test
Tip: This information will be automatically extracted and shown right in the merge request widget.
Caution: On self-managed instances, if a malicious actor compromises the Code Quality job definition they will be able to execute privileged docker commands on the Runner host. Having proper access control policies mitigates this attack vector by allowing access only to trusted actors.

Previous job definitions

Caution: Before GitLab 11.5, Code Quality job and artifact had to be named specifically to automatically extract report data and show it in the merge request widget. While these old job definitions are still maintained they have been deprecated and may be removed in the next major release, GitLab 12.0. You are advised to update your current .gitlab-ci.yml configuration to reflect that change.

For GitLab 11.5 and later, the job should look like:

code_quality:
  image: docker:stable
  variables:
    DOCKER_DRIVER: overlay2
  allow_failure: true
  services:
    - docker:stable-dind
  script:
    - export SP_VERSION=$(echo "$CI_SERVER_VERSION" | sed 's/^\([0-9]*\)\.\([0-9]*\).*/\1-\2-stable/')
    - docker run
        --env SOURCE_CODE="$PWD"
        --volume "$PWD":/code
        --volume /var/run/docker.sock:/var/run/docker.sock
        "registry.gitlab.com/gitlab-org/ci-cd/codequality:$SP_VERSION" /code
  artifacts:
    reports:
      codequality: gl-code-quality-report.json

In GitLab 12.6, Code Quality switched to the new versioning scheme. It is highly recommended to include the Code Quality template as shown in the example configuration, which uses the new versioning scheme. If not using the template, the SP_VERSION variable can be hardcoded to use the new image versions:

code_quality:
  image: docker:stable
  variables:
    DOCKER_DRIVER: overlay2
    SP_VERSION: 0.85.6
  allow_failure: true
  services:
    - docker:stable-dind
  script:
    - docker run
        --env SOURCE_CODE="$PWD"
        --volume "$PWD":/code
        --volume /var/run/docker.sock:/var/run/docker.sock
        "registry.gitlab.com/gitlab-org/ci-cd/codequality:$SP_VERSION" /code
  artifacts:
    reports:
      codequality: gl-code-quality-report.json

For GitLab 11.4 and earlier, the job should look like:

code_quality:
  image: docker:stable
  variables:
    DOCKER_DRIVER: overlay2
  allow_failure: true
  services:
    - docker:stable-dind
  script:
    - export SP_VERSION=$(echo "$CI_SERVER_VERSION" | sed 's/^\([0-9]*\)\.\([0-9]*\).*/\1-\2-stable/')
    - docker run
        --env SOURCE_CODE="$PWD"
        --volume "$PWD":/code
        --volume /var/run/docker.sock:/var/run/docker.sock
        "registry.gitlab.com/gitlab-org/ci-cd/codequality:$SP_VERSION" /code
  artifacts:
      paths: [gl-code-quality-report.json]

Alternatively the job name could be codeclimate or codequality and the artifact name could be codeclimate.json. These names have been deprecated with GitLab 11.0 and may be removed in the next major release, GitLab 12.0.

For GitLab 10.3 and earlier, the job should look like:

codequality:
  image: docker:latest
  variables:
    DOCKER_DRIVER: overlay
  services:
    - docker:dind
  script:
    - docker pull codeclimate/codeclimate:0.69.0
    - docker run --env CODECLIMATE_CODE="$PWD" --volume "$PWD":/code --volume /var/run/docker.sock:/var/run/docker.sock --volume /tmp/cc:/tmp/cc codeclimate/codeclimate:0.69.0 init
    - docker run --env CODECLIMATE_CODE="$PWD" --volume "$PWD":/code --volume /var/run/docker.sock:/var/run/docker.sock --volume /tmp/cc:/tmp/cc codeclimate/codeclimate:0.69.0 analyze -f json > codeclimate.json || true
  artifacts:
    paths: [codeclimate.json]

Configuring jobs using variables

The Code Quality job supports environment variables that users can set to configure job execution at runtime.

For a list of available environment variables, see Environment variables.

Implementing a custom tool

It’s possible to have a custom tool provide Code Quality reports in GitLab. To do this:

  1. Define a job in your .gitlab-ci.yml file that generates the Code Quality report artifact.
  2. Configure your tool to generate the Code Quality report artifact as a JSON file that implements subset of the Code Climate spec.

The Code Quality report artifact JSON file must contain an array of objects with the following properties:

Name Description
description A description of the code quality violation.
fingerprint A unique fingerprint to identify the code quality violation. For example, an MD5 hash.
location.path The relative path to the file containing the code quality violation.
location.lines.begin The line on which the code quality violation occurred.

Example:

[
  {
    "description": "'unused' is assigned a value but never used.",
    "fingerprint": "7815696ecbf1c96e6894b779456d330e",
    "location": {
      "path": "lib/index.js",
      "lines": {
        "begin": 42
      }
    }
  }
]
Note: Although the Code Climate spec supports more properties, those are ignored by GitLab.

Code Quality reports

Once the Code Quality job has completed:

  • The full list of code quality violations generated by a pipeline is available in the Code Quality tab of the Pipeline Details page.
  • Potential changes to code quality are shown directly in the merge request. The Code Quality widget in the merge request compares the reports from the base and head of the branch, then lists any violations that will be resolved or created when the branch is merged.
  • The full JSON report is available as a downloadable artifact for the code_quality job.

If multiple jobs in a pipeline generate a code quality artifact, only the artifact from the last created job (the job with the largest job ID) is used. To avoid confusion, configure only one job to generate a code quality artifact.

If the Code Quality report doesn’t have anything to compare to, no information will be displayed in the merge request area. That is the case when you add the Code Quality job in your .gitlab-ci.yml for the very first time. Consecutive merge requests will have something to compare to and the Code Quality report will be shown properly.

These reports will only be available as long as the Code Quality artifact(s) required to generate them are also available. See artifacts:expire_in for more details.